In one aspect this invention relates to a novel means of mixing a treating fluid with a sample fluid. In another aspect, this invention relates to a fluid mixing and centrifugation apparatus. In still another aspect, this invention relates to an apparatus to be used in the detection of microbial pathogens.
One of the most serious types of blood infections known today is septicemia which is the presence of microorganisms in the blood. The mortality rate for patients who contract septicemia is approximately 25 percent. Furthermore, when shock accompanies septicemia, the mortality rate increases to an alarming 60 percent. Of those particularly susceptible to septicemia are patients who are suffering from debilitating disease, undergoing major surgery, receiving immunosuppressive drugs, or anti-cancer medications.
Because septicemia can cause rapid deterioration of a patient's condition, early diagnosis and treatment are imperative. It is important that a physician not only know that a patient is suffering from septicemia, but also that he be able to readily identify the particular infecting microorganisms. Therefore, a rapid and efficient method of quantitatively analyzing a patient's blood is the first requirement for treating the disease.
The conventional method and equipment which are utilized to detect the presence of microorganisms in the blood suffer from one or more serious drawbacks. These include, lengthy detection time, inability to distinguish different types of microbial pathogens in a blood sample, and the fact that many of these methods do not provide quantitative information. Another major drawback is the risk of contamination by the ambient conditions of the laboratory or by laboratory personnel.
Recently, an improved method of microbial detection has been developed which is extremely rapid and quantitative, and minimizes contamination of the sample from laboratory environment or personnel. This method is disclosed in U.S. Pat. No. 3,928,139, issued Dec. 23, 1975 and entitled "Detection of Microbial Pathogens". According to this improved method for the detection of microbial pathogens, a sample of body fluid such as blood (preferably a lysed blood sample) is deposited upon a liquid filter medium within the confined sterile zone. The liquid filter medium has a density greater than the sample fluid and comprises a sterile aqueous solution which will selectively receive microbial pathogens from the sample fluid. Thereafter, the confined sterile zone is subjected to centrifugation to force the sample fluid against the liquid filter medium and cause the microbial pathogens to selectively pass therein and thereby separate from the mass of the body fluid sample. Next, the liquid filter medium containing the microbial pathogens is separated from the remainder of the sample fluid and portions of the liquid filter medium are subjected to culturing conditions. Improved types of apparatus for carrying out this novel method are disclosed in U.S. Pat. No. 3,875,012, issued Apr. 1, 1975 entitled "Apparatus and Method for the Detection of Microbial Pathogens" and in Applicant's copending application Ser. No. 535,148, filed Dec. 20, 1974 entitled "Mixing and Centrifugation Device".